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DSC Application for Microstructure Investigations of Medieval Cu Alloys

Konieczny J., Labisz K., Głowik-Łazarczyk K., Surma S., Wierzbicki Ł., Jurczyk S.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 2

21--26

EN

Archaeometallurgical investigations presented in this work focus on analysing the microstructure as well as mechanical properties of artefacts from the17th in form of findings performed from cast iron as well as copper casts. The presented research results extend the up-to-date knowledge and present the analysis of structural compounds found in the microstructure of the artefacts from the time dating back to the late Middle Ages in the region around Czestochowa, Poland. The tested samples were found in earth in the city centre under the present marketplace. The excavation works were carried out in summer in the year 2009, and have resulted in the excavation of artefacts in form of copper block of the weight of several kg. The excavation action was led by a group of Polish archaeologists collaborating with the local authorities. The performed pre-dating of this element determines the age of the artefacts as the 17th century AD. The excavations that have been taking place since 2007 have widened the knowledge of the former Czestochowa. Historians of this town have suggested, that the found weight and traces of metallurgical activity suggest that the exposed walls were an urban weight. The weight is visible on the 18th century iconography. What was find on the Old Market indicates that there was a lush economic life before the Swedish invasion in this part of Poland. Some buildings lost their functions or were changed, others died in fires, but new places developed. To describe the microstructure, with its structural components, research was done using microscopy techniques, both of the light as well as electron microscopy (SEM), also chemical composition analysis was carried out using the EDS technique, as well as tool for phase analysis were applied in form of X-Ray Diffraction (qualitative analysis), especially for the reason to describe the phases present in the excavated material. This research will help to obtain new information in order to investigate further archaeometallurgical artefacts, extending the knowledge about middle age metallic materials its usage and manufacturing.

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Application of Differential Scanning Calorimetry (DSC) in study of phase transformations in ductile iron

Przeliorz R., Piątkowski J.

Archives of Foundry Engineering

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2010

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Vol. 10, iss. 2

135--140

EN

The effect of heating rate on phase transformations to austenite range in ductile iron of the EN-GJS-450-10 grade was investigated. For studies of phase transformations, the technique of differential scanning calorimetry (DSC) was used. Microstructure was examined by optical microscopy. The calorimetric examinations have proved that on heating three transformations occur in this grade of ductile iron, viz. magnetic transformation at the Curie temperature, pearlite→austenite transformation and ferrite→austenite transformation. An increase in the heating rate shifts the pearlite→austenite and ferrite→austenite transformations to higher temperature range. At the heating rate of 5 and 15°C/min, local extrema have been observed to occur: for pearlite→austenite transformation at 784°C and 795°C, respectively, and for ferrite→austenite transformation at 805°C and 821°C, respectively. The Curie temperature of magnetic transformation was extrapolated to a value of 740°C. Each transformation is related with a specific thermal effect. The highest value of enthalpy is accompanying the ferrite→austenite transformation, the lowest occurs in the case of pearlite→austenite transformation.

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The unfrozen water content in frozen cohesive soils in the light of DSC results

Kozłowski T.

Zeszyty Naukowe. Inżynieria Środowiska / Uniwersytet Zielonogórski

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2007

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nr 134 (14)

89-99

EN

Results of determination of the unfrozen water function in frozen soilwater system involving analysis of the DSC signal in terms of convolution has been presented. Four homoionic forms of bentonite (Ca2+, Mg2+, Na+ and K+) and two homoionic forms of kaolin (Ca2+ and Na+) were used in the experimental program. Analysis of the obtained results suggests that the process of the ice melting in the soil-water system is not a continuous phase change. The existence of five separate stages of the phase change process during warming from -28°C has been indicated. Three of them, I, III and V, are characterised by quite a vanishing of the phase effects. The intensity of the phase effects during stage IV near the melting point T_f is almost two orders of magnitude greater than in the low-temperature stage II. AdditionaIly, many micro-stages without any phase changes were observed and among them, a characteristic significant stage III directly before the final melting called "the plateau".

PL

W pracy przedstawiono wyniki wyznaczenia zawartości wody niezamarzniętej jako funkcji temperatury w zamarzniętych systemach woda-grunt. Analizę sygnału różnicowej kalorymetrii skaningowej DSC przeprowadzono przy założeniu, że stanowi on konwolucję szukanego rozkładu rzeczywistych efektów termicznych q(T) i funkcji aparaturowej a(T). Porównując wyniki konwolucji zbioru hipotetycznych rozkładów z funkcją aparaturową, znajdowano taki rozkład impulsów q(T), który w konwolucji z funkcją aparaturową dawał najmniejsze odchylenie od obserwowanego sygnału DSC. Tym samym stało się możliwe precyzyjne wyznaczenie krzywej zmian zawartości wody niezamarzniętej w funkcji temperatury. W programie badawczym wykorzystano cztery monojonowe formy bentonitu bentonite (Ca2+, Mg2+, Na+, K+) i dwie monojonowe formy kaolinu (Ca2+ i Na+). Analiza otrzymanych krzywych sugeruje, że proces topienia lodu w systemie wodno-gruntowym nie jest ciągłą przemianą fazową. Wykazano istnienie pięciu osobnych etapów zmiany składu fazowego w trakcie ogrzewania od -28°C. Trzy z nich, I, III i V, charakteryzuje całkowity zanik efektów fazowych. Natomiast intensywność efektów fazowych na etapie IV w pobliżu punktu rozmarzania T_f jest dwa rzędy wielkości większa niż na niskotemperaturowym etapie II. Dodatkowo obserwowano wiele mikro-etapów bez przemiany fazowej, a wśród nich charakterystyczny etap III, nazwany "plateau", bezpośrednio przed końcowym rozmrożeniem.

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Zastosowanie materiałów fazowo-zmiennych do akumulacji ciepła

Pielichowski K., Flejtuch K.

Gospodarka Paliwami i Energią

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2003

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nr 1

7-12

PL

Problem efektywnego wykorzystania energii cieplnej pochodzącej z różnych źródeł ciepła jest przedmiotem badań w wielu ośrodkach naukowych na świecie. Z problemem tym nierozerwalnie związane jest zagadnienie magazynowania ciepła oraz konieczność opracowania układów zdolnych do jej akumulacji. Artykuł obejmuje aktualny stan wiedzy na temat układów zdolnych do akumulacji ciepła wykorzystujących efekty termiczne towarzyszące odwracalnym przemianom fizykochemicznym. Wymieniono rodzaje akumulatorów ciepła oraz przedstawiono związki stosowane jako materiały fazowo-zmienne (PCM), zarówno nieorganiczne jak i organiczne - parafiny, wyższe kwasy karboksylowe i ich estry oraz wybrane polimery. Stosując metodę różnicowej kalorymetrii skaningowej (DSC) ukazano wpływ ciężaru cząsteczkowego na zawartość fazy krystalicznej w związkach wielkocząsteczkowych.

EN

New research directions towards better methods of accumulation of the thermal energy from different renewably energy sources is nowadays a subject of works in numerous scientific centres in the world. In this work current state of knowledge on thermal energy storage systems that exhibit thermal effects due to chemical reactions and physical transitions was presented. Different kinds of thermal storage systems were named and compounds used as phase change materials (PCMs), both inorganic and organic-paraffins, fatty acids and their esters and chosen polymers were presented. Using differential scanning calorimetry (DSC) the influence of molecular weight on the amount of crystalline phase was shown. Demands of contemporary materials engineering for PCMs and perspectives of novel applications were described.